Climate Watch

By Rick Thoman Alaska Climate Specialist Alaska Center for Climate Assessment and Policy International Arctic Research Center/University of Alaska Fairbanks

Sea ice in the Bering Sea had a slow start in November due to mild and stormy weather, but then grew quickly in the colder weather that prevailed through most of December.

Since then, sea ice has gone through a couple of cycles of increasing and then decreasing extent, with the pack ice edge still more than 100 miles north and northeast of St. Paul Island.

In the northern Bering Sea, shortlived areas with low concentration ice have been seen in some areas, including in early February at least a day or two of (nearly) open water between Little and Big Diomede. But what about ice thickness? One of the most important advances in recent years for Arctic regions has been the advent of sea ice thickness estimates by satellites. Unlike sea ice extent, which can be derived from satellites with technology that has been available since the 1970s, sea ice thickness is much more difficult, and that technology has been routinely available for only about a dozen years. It turns out that entirely different methods need to be used for ice that is more than about three feet thick, compared to thinner ice. Now as everyone in western Alaska knows, sea ice quality and thickness often varies dramatically over very short distances, so satellite estimates can, at best, only represent the typical thickness over many square miles. One way we can use these comparatively new products is for year-to-year comparison. The graphic shows that compared to the same time last year, sea ice for the week ending February 9 was thinner than 2023 over much of western Norton Sound northward to the east side of the Bering Strait, while ice in eastern Norton Sound and around St. Lawrence Island was generally similar to this time in 2023. Now as a reminder, with daylight rapidly lengthening and people getting out on the ice, remember the UAF Sea Ice Radar mounted on a tower on jetty at the Port is available online and can provides a good look at both how ice is moving around and an estimate of how far out the shorefast ice extends.

https://seaice.alaska.edu/gi/observatories/nome_radar/

But as always, remember that technology is just one tool and your experience and elder’s knowledge are an important part of staying safe on sea ice.